Wheelchairs are an important means of transportation for a significant portion of society. Whether manually propelled or powered, wheelchairs provide an important degree of independence for those they assist. However, this degree of independence can be limited if the wheelchair is required to traverse obstacles such as, for example, curbs that are commonly present at sidewalks and other paved surface interfaces, and door thresholds. Accordingly, power wheelchairs have been the subject of increasing development efforts to provide handicapped and disabled persons with independent mobility to assist them in leading even more normal and active lives.
To aid in climbing curbs, some power wheelchairs typically have a pair of forward extending anti-tip assemblies that are rotatably coupled to the wheelchair frame. The arm members of the anti-tip assemblies are rotatably coupled to the wheelchair frame such that when the wheelchair encounters a curb, the anti-tip assemblies will pivot upwardly to thereby allow the wheelchair to traverse the curb. Some power wheelchairs also have elevatable seats that permit the occupant to move at “eye-level” with persons walking with them. However, wheelchairs operating with seats at elevated positions are susceptible to instability under certain conditions, and anti-tip assemblies, while beneficial for climbing obstacles such as curbs, may contribute to the instability when the wheelchair is operating on other than flat, level ground.